Highly sensitive electrochemical sensor based on phosphonate-functionalized HKUST-1 for simultaneous detection of Zn(II), Pb(II), and Cu(II)

초록

A phosphonate-functionalized HKUST-1 (P-HKUST-1) electrode was developed for sensitive electrochemical detection of Zn2+, Pb2+, and Cu2+ ions. Density functional theory (DFT) calculations reveal strong metal--framework interactions, with adsorption energies of-0.914 eV (Zn),-1.105 eV (Pb), and-0.797 eV (Cu), markedly stronger than those on pristine HKUST-1, confirming the role of phosphonate groups in enhancing binding affinity. Complementary analyses including extended X-ray absorption fine structure (EXAFS), total and projected density of states (DOS), Fukui function, and electrostatic potential (ESP) mapping elucidated the reversible M2+ <-> M0 redox mechanism and coordination-driven stabilization of metal species. Electrochemical studies demonstrate improved charge-transfer kinetics and enlarged electroactive surface area. Under optimized conditions, anodic stripping square-wave voltammetry (ASWV) enabled trace-level detection with limits of detection of 0.666 & micro;g L-1 (Zn2+), 1.183 & micro;g L-1 (Pb2+), and 0.815 & micro;g L-1 (Cu2+), with excellent reproducibility (RSD: 1.744%, 1.385%, and 0.754%, respectively). Competitive-ion studies show CO32-and PO43-influence metal binding, with carbonate exerting stronger interference. The sensor exhibits high selectivity, reproducibility, and effective performance in real water samples, highlighting P-HKUST-1 as a robust platform for environmental heavy-metal monitoring.

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